Combined rate of flow, pressure and temperature gage

ABSTRACT

A UNITARY PROBE HAVING FOUR STRAIN GAGES AND A CANTILEVER VANE MOUNTED ON A WALL OF THE PROBE. DISPLACEMENT OF THE VANE DUE TO FLUID FLOW IS MEASURED BY TWO OF THE STRAIN GAGES WHILE ANOTHER TWO SENSE PRESSURE WHEN THE PROBE IS ADJUSTED TO STOP FLUID FLOW. TEMPERATURE MAY BE DETERMINED BY APPROPRIATE CONNECTION OF THE GAGES INTO A STRAIN GAGE BRIDGE.

May 9, 1972 D. WIEBE E'TAL COMBINED RATE OF FLOW, PRESSURE AND TEMPERATURE GAGE Original Filed Sept. 17 1964 4 Sheets-Sheet 1 INVENTORS DONALD W/EDE' 8 BY RICHARD B. DOORLE Y I ATTORNEY May 9, 1 972 w E ETAL Re. 27,354

GQIIBINED RATE OF FLOW, PRESSURE AND TEMPERATURE GAGE Original Filed Sept. 17, 1964 4 Shoots-Shut 2 INVEN'TORS DONALD W/EBE 8 RICHARD 8. DOORLEY x/ww ATTORNEY 4 Sheets-Sheet 3 D. WIEBE ET AL ig. l0

p rL May 9, 1972 COMBINED RATE OF FLOW, PRESSURE AND TEMPERATURE GAGE Original Filed Sept.

\ zvlllllllrlllllllllll INVQflVTURS DCHM4LL %EZHF 8 BY R/CHARD B. DOOR/.5)

ATTORNEY May 9, 1972 w|EBE ETAL Re. 27,354

PRESSURE AND TEMPERATURE GAGE COMBINED RATE OF FLOW,

Original Filed Sept. 17, 1964 4 Sheets-Sheet 4.

llbw,

H6 lls INVENTORS DONALD W/EBE 8 BY RICH/IRE B. DOORLEY ATTORNEY Re. 27,354 Reissued May 9, 1972 United States Patent Oihce- Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; inatter printed in italics indicates the additions made by reissue. i

ABSTRACT DISCLOSURE A unitary probe having four strain gages and a cantilever vane mounted on a wall of the probe. Displacement of the vane due to fluid flow is measured by two of the strain gages while another two sense pressure when the probe is adjusted to stop fluid flow. Temperature may be determined by appropriate connection of the gages into a strain gage bridge.

As is known, it is often diflicult to locate the faulty part or parts of a hydraulic or other fluid circuit which is not functioning properly. Such fluid circuits usually consist of a pump, one or more fluid motors or cylinders driven by the pump, and a series of valves for controlling the flow of fluid between the pump and motors. If it should happen, for example, that the power delivered to a fluid motor decreases, the trouble may be due to malfunctioning of any one or more of the many parts of the fluid circuit. While it is possible to progressively dismantle the entire fluid circuit and individually test each part, this is obviously a cumbersome, time-consuming and expensive procedure, particularly when it is remembered that many fluid circuits are complicated and include components and conduits located at inaccessible points within a piece of equipment.

The location of a faulty part in a hydraulic circuit can be determined without dismantling the system by measuring the flow rate, pressure and temperature at various points in the system to isolate a particular faulty unit. In the past, portable circuit testers have been provided which can be connected into the system to determine the rate of flow, pressure and temperature at selected points. While such testers eliminate the necessity for complete dismantling of the system, they nevertheless require that conduits be disconnected at various points in order to connect the tester itself into the circuit. This is not only a cumbersome procedure, but also results in diversion of fluid flow through the tester which alters the characteristics of the fluid circuit.

As an overall object, therefore, the present invention seeks to provide apparatus in the form of a probe which can be inserted into a hydraulic circuit at selected points without requiring any dismantling for the purpose of measuring pressure, rate of flow and temperature.

Another object of the invention is to provide a fluid circuit which permanently incorporates closed cavities of inexpensive, simple construction at spaced points, which cavities can be opened for the reception of a probe which measures rate of flow, pressure and change in temperature.

Another object of the invention is to provide apparatus for determining [measuring] the temperature, rate of flow and pressure of the fluid within a conduit wherein the temperature measuring, pressure measuring, and rate of flow measuring devices are incorporated into a single unitary probe structure.

A further object of the invention is to provide a hydraulic testing device having one or more deformable portions for measuring the pressure and quantity of fluid flow in a hydraulic circuit.

A further object of the invention is to provide a single unitary testing probe for hydraulic and other fluid circuits, which probe incorporates valve means for changing the pressure drop [in the system and its components] by restricting fluid passing through the tester.

Still another object of the invention is to provide a combined pressure and rate of flow tester employing resistance-type strain gages and wherein the gages are external to fluid within a hydraulic circuit being tested.

The above and other objects and features of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings which form a part of this specification, and in which:

FIGS. 1A and 1B illustrate the manner in which the probe of the present invention may be inserted into a fluid conduit;

FIG. 2 is a cross-sectional view of one embodiment of the invention;

FIG. 3 is a broken-away cross-sectional view taken substantially along line IIIIlI of FIG. 2;

FIG. 4 is a view taken substantially along line IVIV of FIG. 2, but with the flow measuring vane removed;

FIG. 5 is a cross-sectional view taken along line VV of FIG. 2 showing the positioning of the resistance-type strain gage devices employed to measure pressure and rate of flow;

FIGS. 6A and 6B are cross-sectional views taken along line VIVI of FIG. 2, showing the manner in which the outlet port of the embodiment of FIG. 2 may be blocked without blocking the inlet port;

FIG. 7 is a broken-away perspective view of the cylindrical insert shown in FIG. 2;

FIG. 8 is a cross-sectional view of another embodiment of the invention;

FIG. 9 is a cross-sectional view taken substantially along line IXlX of FIG. 8 showing the positioning oi the pressure-measuring strain gages of the embodiment of FIG. 8;

FIG; 10 is a view taken substantially along line XX of FIG. 8 showing the positioning of the flow-measuring strain gage elements utilized in the embodiment of FIG. 8;

FIGS. llA-llC illustrate equivalent bridge circuit arrangements in accordance with the invention for measuring pressure, flow rate and temperature;

FIG. 12 is a schematic diagram of the actual circuitry including switches utilized in accordance with the invention for measuring temperature, fluid flow and pressure; and

FIG. 13 is a cross-sectional view of an alternative embodiment of the invention which does not incorporate means for controlling the pressure drop in the system.

Referring now to the drawings, and particularly to FIGS. 1A and 113, a generally cylindrical receptacle 10 is provided with inlet and outlet ports 12 and 14, respectively, adapted for connection to fluid conduits 16 and 18. As will be understood, the fluid conduits are included in a fluid circuit which, in the usual case, includes a pump, one or more fluid motors or cylinders, and valves for controlling the flow of fluid from the pump to the motors or cylinders. The receptacle 10 is permanently connected into the fluid circuit, and a plurality of such receptacles may be spaced at selected testing points throughout the circuit.

As will hereinafter be explained, one end of the receptacle is open and will receive cap 11 which prevents the escape of fluid from the receptacle under normal oprating conditions. The cap 11, however, may be removed rom the receptacle when the fluid within the circuit i not under pressure, and a generally cylindrical testing robe 22 inserted therein. The probe 22 is provided, as hown with a cap 23 which may be threaded onto the pen end of the receptacle 10 to seal the probe within the eceptacle and hold it in place. If desired, caps 11 could 'e provided on either end of the receptacle 10 to facilitate nsertion of probe 22 into either end.

As will be seen, the probe 22 includes means, prefer- .bly in the form of resistance-type strain gages, for measring both the pressure and rate of flow of fluid passing 1rough conduits 16 and 18, as well as its temperature. he strain gages are connected through a cable 13 to a ieter 15 having three dials or graduations thereon. One ial 17 is calibrated to indicate pressure; another dial 19 1 calibrated to indicate flow rate; and the third 21 is alibrated to indicate temperature. By selectively adjustng a knob on the meter housing 27 for a temperature, ressure or rate of flow setting, any one of these factors my be observed from the position of the pointer on the ieter. In FIG. 1A, the apparatus is shown with the cap n receptacle 10; while in FIG. 1B, the cap 11 is removed .nd the probe 22 inserted, with cap 23 holding it in place.

As best shown in FIG. 2, the cylindrical receptacle 10 I provided with an interior cylindrical cavity 20 which is pen at one end. Received within the cavity 20 is the ylindrical probe 22 which is perhaps best shown in FIG. It comprises a lower skirt portion 24 having diametically opposed ports, shown as inlet and outlet ports 26 nd 28, respectively, adapted to register with the inlet nd outlet ports 12 and 14 in the cylindrical receptacle 0. Secured to the lower skirted portion 24 by means of ins 30 or other suitable fastening means is an upper ylindrical portion 32 having formed therein an integral ircular wall 34. The upper inner peripheral surface of the ortion 32 is threaded as at 36 to receive a cap integral with a stub shaft 38 (FIG. 2) which extends through a ore 40 in the cap 23 threadedly received over the open 1nd of the receptacle 10.

With the arrangement shown, a fluid chamber 44 is ormed between the lower surface of wall 34 and the ower end wall of the cavity 20. This chamber 44 comnunicates with the inlet and outlet ports 12 and 14. Conequently, if fluid is flowing between conduits 16 and 18, he entire chamber 44 will be filled with fluid. Above the vall 34 is a second chamber 46 which is isolated from :hamber 44 by means of an O-ring seal 48 provided in an tnnular slot in the shaft 38. The chamber 46, in turn, comnunicates with the atmosphere through an axial bore 0 in the shaft 38. Although not shown in FIG. 2, the able 13 extends through bore 50 for connection to reistance-type strain gages, hereinafter described. Fluid in hamber 44 is prevented from escaping around the edges vf probe 22 and out through the bore 40 by means of an )-ring seal 52 carried Within a cooperating annular slot ormed in the outer periphery of the shaft 38. Similarly, n O-ring seal 53 prevents the escape of fluid through hreads 55 on the upper end of receptacle 10 which re- :eive cap 23 or cap 11, as the case may be.

With the arrangement just described, the probe 22 may 'e rotated within the cylindrical cavity 20 by applying orque to the portion of shaft 38 extending through the this facilitates measuring the static pressure of fluid within the conduit 16 and also enables partial restriction of ap 23. As best shown in FIGS. 6A and 6B, the wall of he cavity 20 adjacent inlet port 12 is provided with a lot or plenum chamber 54, which will permit limited otation of the probe 22 with respect to the receptacle .0 without disconnecting the inlet ports 12 and 26 and vith suflicient plenum size to insure radial flow symmetry iorts 14 and 28 can be disconnected while the inlet port 7 x 6 is still connected to the conduit 16. As will be seen,

fluid through the circuit to build up the pressure therein while still permitting fluid flow therethrough. At the same time, provision of the slot or countersunk portion in the wall of cavity 20 insures that the fluid, in flowing through inlet port 26 will always strike thesur face of'vane 70, hereinafter described, at right angles regardless of the angular position of probe 22 within the receptacle 10. In FIG. 6A, free fluid flow is permitted through chamber 44 between ports 12 and 14. In FIG..6B, the probe 22 has been rotated to disconnect outlet ports 14 and 28 while inlet port 12 is still connected to port 26 through countersunk portion 54 to enable measurementof static pressure. Integrally formed with the wall 34 is a depending stub shaft 56 which carries, at its lower;extrernity, a cylindrical member 58. As best shown in FIGS. 2, 3 and 4, the cylindrical insert 58 is provided with a .pair ofopposed bores 60 and 62. The bore 62 fits over the lower extremity of the stub shaft 56; while the bore 60 receives a screw 64 which extends through the member 58 and is threaded into the stub shaft 56, thereby securing the member 58 to the shaft 56. Alsoformed in the cylindrical member 58, as best shown in FIG. 4, is a transverse slot 68 which receives a flat vane 70. The flat vane 70 is provided with a cut-out portion 72 (FIG. 3) which enables it to be fitted into the slot 68. Finally, the vane 70 is held within the slot 68 by means of a rivet 74 or other suitable fastening means. v

As is best shown in FIGS. 3 and 7, the width of the vane 70 is slightly less than the inner'per'ipheral diameter of the skirted portion 24; and the vane extends downwardly into the chamber 44 beneath the inlet and outlet ports 26 and 28. There is, however, sufficient space beneath the lower edge of the vane 70 and the bottom of the cylindrical cavity 20 to [facilitate] permit the flow of the major portion of the fluid between the inletand outlet ports 26 and 28 along theapproximate path of the arrows 76 in FIG. 2. When thefiuid from inlet port 26 thus impinges on the left face'of vane. 70 as viewed in FIGQZ, and exerts viscous drag alongthe bottom of vane 70, it will deflect the vane in a counterclockwise direction as illustrated by the arrow 78 inFIG. 2.

With specific reference, now to FIGS. 2, 3, 5 and i7, deflection in the vane 70 will [effect tensile stresses at area 88 and compressive stresses at area 90.], as isknown, cause the wall 34 to be deformed in the manner of a fixed beam with a constant moment applied nearjthe center in the plane of fluid flow normal .to the lwall 34. Such deformation of the wall 34 causes tensionstress to occur in the outer surface of wall v34 near or adjacentthe juncture of wall 34 with the supporting structure therefor in the portion away from which the vanc70 is deformed, a portion of which area of stress is illustratively shown as area 88. Equally known, the deformation -of wall 34 alsocauses compression stress tov occur in the ou t ersurface'ofwall 34 near or adjacent the juncture of wall 34 with, the supporting structure therefor in the portion towards which the vane 70 is deformed- 1 portion of whichareaofi stress is illuslratively shownas area 90. Securedto'the areas-88 and 90 are a pair of resistance-type strain gagesg92 and 94. Strain gages 92 and 94 can assume. any location onsurface 84 as long as one gage measures strain-opposite to .that experienced by the other. ,As will hereinafter .beexplained, the strain gages 92,-and.-94;areconnected-in;a bridge circuit arrangement to.-indicate.-the deflection-in elements 70 and 56 as reflected in the tensile,and compres- .sive. stresses in a radial direc tion; on surface 84 atareas 88 chamber 44, a second pair of strain gages and 98 (FIG.

-, ing means.

) are [secured near the edge and near the center of surface 84.] as shown, along a radius in a plane normal to the direction of fluid flow. In this respect, it is apparent that the wall 34 functions as a diaphragm which is deflected upwardly by the pressure within the chamber 44, the greater the pressure the more the deflection. In response to pressure beneath wall 34, the area beneath strain gage 98 will be placed in tension and that beneath strain gage :96 placed in compression to produce an additive elfect and temperature compensation as will be more fully explained. As known, the stresses in the upper surface of wall. 34 due to such pressure are, near the edge in compression and 'near the center in tension and, accordingly gages 98 and. 96 are located on such areas respectively. The strain gages 92,94, 96 and 98 are connected through the cable 13 (FIGS. 1A and 1B) which passes through bore 50'to the aforesaid bridge circuits, hereinafter described in detail. In this respect, it will be appreciated that none of the strain gages are within the fluid chamber 44;"1'his is a distinct advantage with this embodiment of the invention in that no problems are encountered in pro viding sealing'means around electrical leads passing into the chamber 44 or physically protecting the strain gages from fluid effects, particularly when high pressures are encountered.

While the specific arrangement of flat surfaces 84 and 34 is shown herein for purposes of illustration, it should be understood that other and different arrangements of surface contour 'can be utilized in accordance with the invention for the purpose of obtaining areas of measurable stresses-[stress concentration] in the upper surface of Wall 34in responseto torque or bending moment applied to vane 70. In all cases, however, the flow-rate measuring strain -gages92and 94 will be at the areas [of torqueresponsive stress concentration] responsive to measurable stresses resulting from the bending or deflection 0f vane 70.-

with reference now to FIGS. 8, 9 and 10, another embodiment of the invention is shown which is similar in construction to that shown in FIGS. 2-7. Accordingly, elements in FIGS. 8, 9 and which correspond to those shown in FIGS. 27 are identified by like reference nu- .merals. In thiscase, however, the diaphragm wall 34 is provided with a tapped bore 102 which receives the threaded upper portion of a downwardly-depending stub shaft lMfcarried withina slot in the lower end of the stub shaft 104 is the vane 70, the vane being secured Within the slot by, means of a rivet 106 or other suitable fasten- Instead of providing flow-measuring strain gage devices outside of the chamber 44, the strain gages 92 and 94 in this case are on opposite, flattened surfaces 108 and 110 of thestub shaft 104. Electrical leads for the strain gages 92 and-94 then, pass upwardly through holes 112 in the .shaft' 104, :which holes are filled-with an epoxy resin or the like to prevent escape of the fluid from the chamber 44. Aside from-the positioning of the flow-measuring strain gages, however, the operation of the embodiment ofFIGS. 8-10 is'the same as that previously described.

.Ref e1"ring to FIGS. UA -11C, three circuit diagrams are illustrated for measuring flow rate, pressure and tem- I 'suitably aflixed-such as to apiece of metal positioned, for

example, within the meter housing 27. The bridge circuit vmaybe initially balanced bymeans of rheostat 124; and themeter initially calibrated for a given flow rate by means of rheostat 126 which can be selectively adjusted to a given indicator reading while placing a fixed resistor 143 in parallel with strain gage 94 by means of switch 128.

The meter 15, comprising a galvanometer, is connected between the junction of gages 120, 122 and the junction of gages 92, 94 substantially as shown, to complete the bridge circuit. As will be appreciated, the bridge circuit will be balanced and no current will flow through the meter 15 when the ratio of the impedance of element 92 and part of element 124 with respect to element 94 is equal to that of element and the remaining portion of element 124 with respect to element 122. Thus, the bridge will be balanced when:

where R92, R94, R120 and R122 are the instantaneous resistance values of gages 92, 94, 120 and 122, respectively. R124, the balancing resistor, is assumed small compared to the four principal resistors in the bridge. Since strain gage 92 is placed in tension under flow conditions while strain gage 94 is placed in compression, their combined tension and compression strains are [cumulative] additive in their action on the bridge, thereby increasing the sensitivity considerably beyond what would be obtained with only a single strain gage on Wall 34. Another advantage of the twogage arrangement is that they compensate for temperature changes. Thus, if the temperature of the probe should increase, the wall 34 will expand and the conductivity of the gage wire filaments will change but the net impedances of strain gages 92 and 94 will change in the same amount, the same holds true for the pressure effect, thereby maintaining the same ratio between the two such that the bridge circuit remains balanced and will respond [only to deflections in the vane 70.] to the bending moment resulting from the deflection of vane 70 in a plane parallel to the direction of flow. [The same is true of gages 120 and 122 afiixed to a piece of metal within housing 27 (FIGS. 1A and 1B) at room temperature] Although reference strain gages 120 and 122 other suitable resistance means can be employed, as known, in the bridge circuits described.

In FIG. 11B the equivalent bridge circuit arrangement for pressure readings is shown wherein elements corresponding to those shown in FIG. 11A are identified by like reference numerals. In this case, however, the series arrangement of pressure strain gages 96 and 98 is connected in parallel with the series combination of strain gages 120 and 122. Thus, the reading of meter 15 will be responsive to pressure rather than flow rate. The bridge is initially balanced by rheostat 130 and calibration effected by elements 132 and 134 and 144 in the manner described in connection with FIG. 11A. Again, by virtue of the positioning of the strain gages 96 and 98, one will be in compression and one will be in tension, thereby providing [a cumulative] an additive effect on the bridge circuit while at the same time compensating for temperature variations since the ratio of the impedance of element 96 with respect to element 98 will remain constant as long as the expansion or contraction in the two is the same as a result of temperature variations.

In FIG. 110, the equivalent bridge circuit configuration for temperature measurements is shown wherein elements corresponding to those shown in FIGS. 11A and 11B are again identified by like reference numerals. In this case, however, the strain gages 120 and 122 external to the probe 22 are in opposing legs of the bridge circuit, as are the flow-measuring strain gages 92 and 94. The bridge is initially balanced by rheostat 136, and calibration effected by elements 138 and 140. The strain gages 120 and 122 will be at ambient temperature (i.e., room temperature). The strain gages 92 and 94, however, will be responsive to the temperature of the fluid within the chamber 44. Now the bridge will be balanced only when:

7 Llld again the resistance of element 136 is small compared the remaining bridge elements. Let us assume, for extmple, that the temperature of fluid within the chamber 14 increases. Under these circumstances, the impedances {92 and R94 of the strain gages 92 and 94 will be aslllIIld to increase. This unbalances the bridge, and the mbalance is again additive [cumulative]. At the same ime, changes in the flow rate, for example, will not afect the bridge circuit configuration of FIG. 11C since [11 increase in the impedance R92 of element 92 due to tn increase in the flow rate, for example, will be com- )ensated for by an equal and opposite decrease in the mpedance R94 of the element 94. The bridge circuit coniguration of FIG. 11C, therefore, is responsive only to emperature variations or differences between the meter lIld flow measuring element. As will be understood, the ;train gages 92 and 94 could be replaced by the pressure responsive strain gages 96 and 98 if desired with :qual effectiveness.

In FIG. 12 the switching arrangement for effecting the :quivalent bridge circuits shown in FIGS. 11A, 11B and 11C is illustrated. It includes a rotary switch element havng a plurality of movable wipers W1-W12 thereon me- :hanically interconnected as by a common shaft schematizally illustrated by the reference numeral 142 and coniected to dial 25 such that all of the wipers will be on heir No. 1, No. 2 or No. 3 contact simultaneously.

With the wipers in the position shown in FIG. 12 wheren they are connected to the No. 1 contacts, the flow neasuring bridge circuit arrangement of FIG. 11A is effected. Thus, input terminal 118 is connected through 'heostat 126, 124 and wiper W1 to the strain gage 92. [be other end of the strain gage 92 is connected through viper W2 to one input terminal of the meter 15 and .hrough wiper W3 to one end of the strain gage 94. The ther end of the strain gage 94 is then connected through viper W4 to input terminal 116. At the same time, the :xternal strain gages 120 and 122 are connected between nput terminals 116 and the rheostat 124 through wipers W5, W6, W7 and W8. This, in effect, completes the bridge :ircuit arrangement of FIG. 11A.

To effect the pressure measuring bridge circuit arrangenent of FIG. 11B, all of the wipers are moved to their T0. 2 contacts. Under these circumstances, strain gages i2 and 94 are disconnected from the circuit, while strain gages 96 and 98 are connected into the circuit through wipers W9, W10, W11 and W12. Thus, with the wipers )n the No. 2 contacts, a circuit is completed from input :erminal 118 to rheostats 132, 130, wiper W9, strain gage )6, wiper -W to one input terminal of meter 15. This aame terminal of meter is connected through wiper W11, strain gage 98 and wiper W12 to input terminal 116. The connections of the strain gages 12.0 and 122 to the neter 15 are the same as before; however their opposing ands are now connected through wipers W5 and W8 to nput terminal 116 and rheostat 130, respectively, rather :han rheostat 124.

In order to measure temperature, the wipers are moved :0 their No. 3 contacts, in which case the rheostats 138 and 136 are connected in a bridge circuit arrangement with elements 92, 94, 120 and 122 to effect the equivalent :ircuit of FIG. 11C.

With reference, now to FIG. 13, a still further embodinent of the invention is shown wherein the annular skirt jortion'24 is eliminated. The probe 22 in this simply comprises a cup-shaped upper portion 150 whichrests on a ihoulder 152 formed in the receptacle 10. In this case, of :ourse, the probe is not rotatable within the chamber 44, aor is it possibleto vary the pressure drop within the system. An arrangement such as that shown in FIG; 13, may be used, for example, as a permanent insert intoa Fluid circuit for the purpose of continually measuring dynamic pressure, flow rate and/or temperature.

Although the invention has been shown in connection with certain specific embodiments, it will be readily apparent to those skilled in the art that various changes in form and arrangement of parts may be made to suit requirements without departing from the spirit andscope of the invention.

What is claimed is: I I

1. In a hydraulic circuit, a normally closed receptacle having inlet and outlet ports permanently connected to the hydraulic circuit such that fluid in the circuit will flow through said receptacle, cap means on said receptacle which maybe removed to expose the interior of the receptacle, a testing probe insertable into said receptacle with the cap means removed 'for measuring a characteristic of the fluid in'the circuit, and means on the testing probe for controlling the ratebf fluid flow through said receptacle."

2. In a hydraulic circuit, a' normally closed generally cylindrical receptacle having inlet and outletports in its walls permanently connected "to the hydraulic'fcircuit such that fluid in the circuit will flow through said receptacle, cap means on one end of said cylindrical receptacle which may be removedto expose the interior of the receptacle, and a testing probe insertable into said receptacle with the cap means removed for measuring a characteristic of thefluid within the hydraulic circuit, said testing probe including a generally cylindrical skirt portion rotatable within said receptacle and having irflet and outlet ports in its walls adapted to selectively register with the inlet and outlet ports'of said receptacle'whe'reby fluid flow through the skirt portion'may be controlled by rotation of the skirtportion withinthe cylindrical receptacle, and means carried on said probe for. .determining a characteristic of the fluid Within saidjhydra ulic circuit. v

3. The combination of claim 2' wherein the "means carried on said probe for determining a characteristic of the fluid comprises a device for measuring rate of fluid flow in said hydraulic circuit.

4. The combination of claim 2 wherein the means carried on said probe for determining a 'c'ha'racteristic of the fluid comprises a device formeasuring th pre'ssure of the fluid within said hydraulic circuit. p I

5. The combination of claim 2 wherein the means carried on said testing probe for determining a characteristic of the fluid [comprises a device for measuring the temperature of the fluid within said hydraulic circuit] includes means responsive to changes in temperuturefof the fluid in said hydraulic circuit. V i

6. In a hydraulic circuit, a normally'closed' generally cylindrical receptacle having inlet and outlet ports in its wall permanently connected to the hydraulic circuit such that fluid in the circuit will flow through said receptacle, cap means on one end of said cylindrical receptacle' which may be removed to expose the interior of the receptacle, and a testing probe insertable into 'said'receptacle'with the cap means removed for measuring both the pressure within the hydraulic circuit as well as th'e'rateof fluid flow therein, said testing probe" including a' generally cylindrical skirt portion rotatable within said receptacle and having inlet and outlet ports in its walls adapted to selectively register with the inlet and outlet ports of said receptacle whereby fluid flow. through the skirt portion may be controlled 'by rotation of the skirtportionwithin the cylindrical receptacle, vane-type fluid flow [measuring] determining means incorporated into said probe for [measuring] determining the rate of ,fluid flow between said inlet and outlet ports, and diaphragm-type pressure [measuring] determining means incorporated into said probe for [measuring] determiuingthe pressure of the fluid within said hydraulic circuit.

7. The combination of claim 6 wherein said skirt portion is provided with a stub shaft which projects dut of said receptacle with the skirt portion inserted therein, and annular cap means surrounding said stub shaft'portion for sealing the skirt portion, theflowmeasuringand the pressure measuring means Within-the receptacle while permitting rotation of the skirt portion by application of torque to said stub shaftportion.

8. A device for measuring both the fluid flow within a wnduit as well as the pressure therein comprising, a chamber having inlet and outlet ports adapted for connection to a conduit such that fluid passing through the conduit will flow into the chamber through the inlet port and out through the outlet port, said chamber being formed in part by a deformable wall said wall being spaced from said inlet and outlet ports, [a wall in said chamber, said wall extending generally parallel to the direction of fluid flow through the chamber,] an element rigidly fixed to said wall and extending into said chamber [at generally right angles to the flow of fluid therethrough] whereby the element will be deflected by fluid flowing between the inlet and outlet ports, first strain gage means secured to the side of the wall opposite said element [for measuring deflection in said element and hence the rate of fluid flow through said chamber] responsive to stresses in said wall resulting from deflection 01f said element for sensing fluid flaw through said chamber and second strain gage means secured to said side of the wall opposite said element [for measuring deflection in said wall and hence the pressure within the chamber] responsive to stresses in said wall resulting from the pressure of fluid within said chamber for sensing the fluid pressure within said chamber.

9. A device for measuring both the fluid flow within a conduit as well as the pressure therein, comprising a chamber having inlet and outlet ports adapted for connection to a conduit such that fluid passing through the conduit will flow into the chamber through the inlet port and out through the outlet port, a wall at one end of said chamber, [said wall extending generally parallel to the direction of fluid flow through the chamber,] a cantilever vane [having one end rigidly] fixed to said wall [and] with the [anjlunsupported end projecting into the interior of said chamber [at generally right angles to the flow of fluid therethr-ough] whereby the vane will be deflected by fluid flowing between the inlet and outlet ports, resistance-type strain gage means in contact with said wall [for measuring deflection in said vane and hence the rate of fluid flow through said chamber] responsive to stresses in said wall resulting from deflection of said vane and resistance-type strain gage means in contact with said wall [for measuring deflection in said wall along the axis of said vane and hence the pressure within the chamber] responsive to stresses in said wall resulting from the pressure of fluid within said chamber.

10. A device for measuring fluid flow within a conduit comprising a chamber having axial extent along a given axis and having inlet and outlet ports extending transversely of said given axis and adapted for connection to a conduit such that fluid passing through the conduit will flow into the chamber through the inlet port and out through the outlet port, a wall at one end of said chamber,said wall being spaced from said inlet and outlet ports and extending transversely of said given axis, [said wall extending generally parallel to the direction of fluid flow through the chamber,] a cantilever vane having one end rigidly fixed to said wall and an unsupported end projecting into the interior of said chamber [at generally right angles to the flow of fluid therethrough whereby] such that the vane will be deflected by fluid flowing between the inlet and outlet ports, means incorporated into said wall for providing areas of measurable stress [concentration] in response to deflection of said vane when fluid flows through said chamber, and resistance-type strain gage means in contact with said areas of measurable stress [concentration for measuring deflection in said vane and hence] for determining the rate of fluid flow through said chamber.

11. A device for measuring both the rate of fluid flow within a conduit as well as the pressure therein,

comprising a chamber having inlet and outlet ports adapted for connection to a conduit such that fluid passing through the conduit will flow into the chamber through the inlet port and out through the outlet port, a wall at one end of said chamber, [said wall extending generally parallel to the flow of fluid throughthe chamber,] a cantilever vane having one end rigidly fixed to said wall and an unsupported end projecting into the interior of said chamber such that [at generally right angles to the flow of fluid therethrough whereby] the vane will be deflected by fluid flowing between the inlet and outlet ports, a first pair of resistance type strain gage devices on the side of the wall opposite said vane and spaced along a line [extending parallel to the flow of fluid through the chamber], bridge circuit means operatively connected to said first pair of strain gage devices [for indicating deflection in said vane] responsive to said stresses in said wall resulting from the deflection of said vane and hence the rate of flow of fluid through said chamber, a second pair of resistance-type strain gage devices secured to said side of the wall opposite the cantilever vane, and bridge circuit means operatively connected to said second pair of strain gage devices [for indicating deflection in the wall and hence] responsive to stresses in said wall re sulting from the pressure within the chamber.

12. A device for measuring both the fluid flow within a conduit as well as the pressure therein, comprising a generally cylindrical receptacle having inlet and outlet ports in its walls adapted for connection to a hydraulic circuit, a hollow cylindrical insert received within said receptacle and having inlet and outlet ports in its walls adapted to register with the ports in said receptacle, said hollow cylindrical insert having an integral generally circular wall at one end thereof, a cantilver vane having one end rigidly fixed to said circular wall [and an] with the unsupported end projecting into the interior of said hollow cylindrical insert [at generally right angles to the flow of fluid between the inlet and outlet ports in the walls of said insert], first strain gage means on said circular wall and responsive to deflection in said wall for [measuring] determining the pressure within said hollow cylindrical insert, and second strain gage means on said circular wall and responsive to deflection of said vane for [measuring] determining the rate of fluid flow between said inlet and outlet ports.

13. A device for measuring both the fluid flow within a conduit as well as the pressure therein, comprising a generally cylindrical receptacle having inlet and outlet ports in its walls adapted for connection to a hydraulic circuit, a hollow cylindrical insert received within said receptacle and having inlet and outlet ports in its walls adapted to register with the ports in said receptacle, said outlet ports being of generally the same cross-sectional area and one of said inlet ports being of larger cross sectional area than the other inlet port whereby the cylindrical insert may be rotated to block fluid flow between said outlet ports without disconnecting said inlet ports, said hollow cylindrical insert having an integral generally circular wall at one end thereof, a cantilever vane having one end rigidly fixed to said circular wall [and an] with the unsupported end projecting into the interior of said hollow cylindrical insert [at generally right angles to the flow of fluid between the inlet and outlet ports in the walls of said insert], first strain gage means on said circular wall and responsive to deflection in said Wall for [measuring] determining the pressure within said hollow cylindrical insert, and second strain gage means on said circular wall and responsive to deflection of said vane for [measuring] determining the rate of fluid flow between said inlet and outlet ports. 5

14. The device of claim 13 wherein the cantilever wine is generally rectangular, is coaxial with the axis of said cylindrical insert, and has a width slightly smaller than the inner diameter of said cylindrical insert.

15. The device of claim 13 wherein the cylindrical insert has a projection extending beyond said integral generally circular wall, and a generally annular cap surrounding said projection for holding the cylindrical insert within said cavity and for hydraulically sealing the cylindrical insert within said cavity.

16. A device for measuring the rate of fluid flow within a conduit as well as the pressure and temperature of the fluid therein, comprising fluid-flow measuring means having a first pair of resistance-type strain gage devices thereon and responsive to the flow of fluid through said conduit, diaphragm means having a second pair of resistancetype strain gage devices thereon and responsive to pressure within said conduit, a third pair of resistance-type strain gage devices positioned external to said fluid conduit, first bridge circuit means adapted for connection to said first and third pairs of strain gage devices [for indicating] to be responsive to changes in the rate of fluid flow through said conduit, second bridge circuitt means adapted for connection to said second and third pairs of strain gage devices [for indicating] to be responsive to changes in the pressure of the fluid within said conduit, and third bridge circuit means adapted for connection to said third pair of strain gage devices and one pair of said first and second pairs of strain gage devices [for indicating] to be responsive to changes in the temperature of fluid within said conduit.

17. The device of claim 16 including switch means for selectively interconnecting said first, second and third pairs of strain gage devices to effect said first, second and third bridge circuit means.

18. A device for measuring both the fluid flow within a conduit as well as the pressure therein, comprising a chamber having inlet and outlet ports adapted for connection to a conduit such that fluid passing through the conduit will flow into the chamber through the inlet port and out through the outlet port, diaphragm means in one wall of the chamber arranged such that the pressure of the fluid within the chamber will cause deflection in the diaphragm means and hence the pressure within the chamber, a cantilever lvane having one end rigidly fixed centrally to said diaphragm means [and an] with the unsupported end projecting into the interior of said chamber [at generally right angles to the flow of fluid therethrough] whereby the vane will be deflected by fluid flowing between the inlet and outlet ports, and means associated with said diaphragm means for [measuring] determining deflection in said vane and hence the rate of fluid flow through said chamber.

19. In a hydraulic circuit, a normally closed receptacle having inlet and outlet ports permanently connected to the hydraulic circuit such that fluid in the circuit will flow through said receptacle, cap means on said receptacle which may be removed to expose the interior of the receptacle, a testing probe insertable into said receptacle with the cap means removed for measuring a characteristic of the fluid in the circuit, spaced wall portions on the testing probe, passageways in the spaced wall portions, and means for moving the flow control member within the hollow housing member to thereby move the passageways in said spaced wall portions into and out of registry with said inlet and outlet ports to thereby vary the rate of fluid flow between the inlet and outlet ports.

"'20. A device for sensing characteristics of a fluid circuit comprising a hollow housing member having inlet and outlet ports adapted for connection to a fluidcircuit such that fluid can flow through the housing, a flow control member within the housing member and having spaced wall' portions, passageways in the spaced wall por- 70 tions, meansfor moving the flow control member within 12 of fluid flow between the inlet and outlet ports, and a fluid characteristic sensing element positioned within said housing member. I

21. A hydraulic characteristic measuring device comprising, a closed chamber having an axial extent along a given axis and having inlet and outlet ports extending transversely of said given axis spaced to permit hydraulic fluid to flow therethrough, said chamber having a wall member spaced from said inlet and outlet ports and'extending transversely of said given axis with first portions thereof being deformable in. a measurable amount proportional to the pressure'ofsuch fluid during such flow, said wall member having acantilever member extending within said chamber located with respect to said ports that hydraulic fluid during such' flow 'is'efiectivethereon to deform second portions of said wall member in "a measurable amount proportional to the qua'n'tity of hydraulic fluid flowwing during suchflow," strain measuring means mounted on selected ones of said portions 'in -21 manner that a characteristic thereojchanges in proporportion to the deformation of said wall member, and said strain measuring means being adapted to be connected to means for indicating said characteristic thereof. 22. A device as setfforth in claini' 21 in which said strain measuring means is mounted 'on said first portions, additional strain measuring means mounted on portions of said extending member in a manner that a characteristic thereof changes in proportion to the deformation of said extending member, and said" additional strain measuring means being adaptedto be connected tomeans for indicating said characteristic of said additional strain measuring means. p I 23. A device as set forth in claim 21 in which said r selected ones of said portions are spaced areas of 'sdid first portions, additional strain measuring means mounted on spaced ones of said second portions in a' manner that a characteristic thereof changes in proportion to thedeformation of said wall member, and said additional str'ain measuring means being adapted to be connected to means for indicating said characteristic of said additional strain measuring means. W 24. A device as set forth in claim 21in whichrsaid strain measuring means is connected to means calibrated to indicate a characteristic of such hydraulic fluid in accordance with the value of said characteristic of said strain measuring means. 25. A device as set forth in claim 23 in which said strain measuring means and said additional strain measuring means are connected to means calibrated to indicate a characteristic of such hydraulic fluid in accordance with the value of said characteristics ofsaid strain measuring means and said additional -strain measuring means. 1

References Cited 7 I The following references, cited by the Examiner, are of record in the patented file of this patent ortheorigiiial patent.

UNITED STATES PA N s I, 2,420,148 5/l947 -Ostergren. 735 39801) 2,989,866 6/1961 Widell a a1. 1,683,743 9/1928 Thompson .,73-34 5 I 1,917,317 7/1933 .Nacey 73.228 2,400,467. 5/1246 Ruge- "2,658,434 11/1953 Miller .73 40 .5

I Us. 01. xii. 73168, 228, 344, 345], 

